When blood glucose levels (also called blood sugar levels) are too high, it's called hyperglycemia.

Glucose is a sugar that comes from foods, and is formed and stored inside the body. It's the main source of energy for the body's cells and is carried to each through the bloodstream. But even though we need glucose for energy, too much glucose in the blood can be unhealthy.

Hyperglycemia is the hallmark of diabetes — it happens when the body either can't make insulin (type 1 diabetes) or can't respond to insulin properly (type 2 diabetes). The body needs insulin so glucose in the blood can enter the cells to be used for energy. In people who have developed diabetes, glucose builds up in the blood, resulting in hyperglycemia.

If it's not treated, hyperglycemia can cause serious health problems. Too much sugar in the bloodstream for long periods of time can damage the vessels that supply blood to vital organs. And, too much sugar in the bloodstream can cause other types of damage to body tissues, which can increase the risk of heart disease and stroke, kidney disease, vision problems, and nerve problems in people with diabetes.

These problems don't usually show up in kids or teens with diabetes who have had the disease for only a few years. However, they can happen in adulthood in some people, particularly if they haven't managed or controlled their diabetes properly.

Blood sugar levels are considered high when they're above someone's target range. The diabetes health care team will let you know what your child's target blood sugar levels are, which will vary based on factors like your child's age.

Causes of High Blood Sugar Levels

A major goal in controlling diabetes is to keep blood sugar levels as close to the desired range as possible. It's a three-way balancing act of:

  1. diabetes medicines (such as insulin)
  2. food
  3. activity level

All of these need to be balanced to keep blood sugar levels under control. If any one is off, blood sugar levels can be, too.

In general, problems controlling blood sugar levels are due to one or more of the following:

  • not getting enough insulin or other diabetes medicine
  • not following the meal plan (like eating too much on a special occasion without adjusting medicines)
  • not getting enough exercise
  • illness or stress
  • use of certain medicines that can raise blood sugar, like steroids used to treat inflammation

Signs & Symptoms of Hyperglycemia

The symptoms of hyperglycemia are similar to those that happen when someone is diagnosed with diabetes, such as:

  • Frequent urination: The kidneys respond to high levels of glucose in the bloodstream by flushing out the extra glucose in urine (pee). A child with diabetes who has hyperglycemia may need to pee more often and in larger volumes.
  • Extreme thirst: Kids with hyperglycemia who lose a lot of fluid from urinating often become very thirsty and may drink a lot in an attempt to prevent dehydration.
  • Weight loss despite increased appetite: Without enough insulin to help the body use glucose, the body breaks down muscle and stored fat in an attempt to provide fuel to hungry cells.
  • Fatigue: Because the body can't use glucose for energy properly, kids with hyperglycemia may be unusually tired.

Checking for High Blood Sugar Levels

As part of the diabetes management plan, you'll need to check your child's blood sugar levels multiple times a day with a blood glucose meter. This helps you identify when your child has high blood sugar levels, which don't always cause symptoms. Someone who isn't testing regularly might have blood sugar levels high enough to damage the body without even realizing it.

The HbA1c test can show if someone has been having significant hyperglycemia over time, even though the person may not have had obvious symptoms.

If you find that your child is having a lot of high blood sugar levels, the diabetes health care team may suggest changing the diabetes medicines or meal plan to bring the levels back into a healthy range.

In other cases, an equipment issue, like an insulin pump problem or expired insulin, may be the cause. Make sure you contact the diabetes team if your child's blood sugar levels are often above the target range.

Treating High Blood Sugar Levels

Treating high blood sugar levels means correcting their cause. The diabetes health care team will give you specific advice on how to keep your child's blood sugar levels in a healthy range. But here are some suggestions for managing some causes of hyperglycemia:

 CauseWhat to Do

Not getting enough insulin or other diabetes medication
  • Make sure your child takes the right type of insulin and the correct dose at the right time.
  • Check that the insulin is not expired.
  • Make sure that all equipment (pumps, meters, etc.) works properly.
  • Diabetes medicines may need to be changed or adjusted — check with the diabetes health care team.

Not following the meal plan (like eating too much food on special occasions without adjusting medicines)
  • Work with a registered dietitian to change your child's meal plan as needed.
  • Adjust insulin/pills whenever your child eats more or less than what's on the meal plan (the care team can help you with this).

Not getting enough exercise
  • Help your child make time for exercise.
  • Adjust your child's medicines based on the care team's instructions.

Illness or stress
  • Contact the diabetes health care team.
  • Your child should continue to take insulin (the dose may need to change).
  • Check blood sugar levels often as per the diabetes management plan.

Use of medicines that increase blood sugar
  • Contact the diabetes health care team.
  • Insulin or pills may need to change while your child takes the medicine that's causing high blood sugar levels.

A single high blood sugar reading usually isn't cause for alarm — it happens to everyone with diabetes from time to time. However, consistently high blood sugar levels need to be addressed.

Diabetic Ketoacidosis (DKA)

Insulin lets glucose get into the body's cells. Without enough insulin, the body can't use glucose for energy and starts to use fat for fuel. This can happen, for example, when someone skips doses of insulin or when the need for insulin suddenly increases (for example, due to stress or illness) and the doses are not adjusted.

When the body uses fat for energy, chemicals called ketones are released into the blood, causing diabetic ketoacidosis (DKA). Some of the ketones, like extra glucose, exit the body through urine.

But high levels of ketones in the blood can be a problem because they cause the blood to become acidic. Too much acid in the blood throws off the body's chemical balance.

Diabetic ketoacidosis is a very serious — but completely preventable — condition that can lead to coma or death if it's not treated quickly. It happens more often in people with type 1 diabetes, but can sometimes happen in people with type 2 diabetes.

Signs & Symptoms of Diabetic Ketoacidosis

Symptoms of diabetic ketoacidosis usually don't start all at once — they usually come on slowly over several hours. Signs and symptoms include:

  • fatigue (extreme tiredness)
  • excessive thirst/urination
  • dry mouth and dehydration

These symptoms are caused by the sustained hyperglycemia (usually lasting several hours) that typically happens before someone develops diabetic ketoacidosis.

If the person isn't treated, these symptoms can happen:

  • abdominal pain
  • nausea and/or vomiting
  • fruity (acetone) breath odor
  • rapid, deep breathing
  • confusion
  • unconsciousness ("diabetic coma")

Checking for Diabetic Ketoacidosis

How do you know if your child has diabetic ketoacidosis? The signs and symptoms can mimic or be triggered by other illnesses, like the flu. So, it's very important to check your child's blood sugar levels and urine ketones during illness — especially if there are high blood sugar readings — or if your child has symptoms of diabetic ketoacidosis.

Because high levels of ketones in the blood cause ketones to appear in the urine, ketones can be checked at home by testing a sample of your child's urine. If the urine test for ketones is negative, it generally means that symptoms are not due to diabetic ketoacidosis. If the urine test is positive, contact your child's diabetes health care team. 

Tests done by a lab or hospital can confirm whether a child has diabetic ketoacidosis, if necessary. Some newer blood glucose meters also offer the option of testing blood for ketones. Ask the diabetes health care team if such a meter is a good idea for your child.

Treating Diabetic Ketoacidosis

Diabetic ketoacidosis requires immediate medical treatment with intravenous (IV) insulin and fluids and close monitoring in a hospital. Contact the diabetes health care team immediately or seek emergency care if you think your child is having symptoms of diabetic ketoacidosis.

All adult family members and your child's caregivers and school staff should know about the risk of diabetic ketoacidosis in a child with diabetes, and they should know when to call 911.

In addition, all kids and teens with diabetes should wear some sort of medical identification (like a bracelet or necklace) and/or carry medical identification (ID) information at all times. Besides identifying your child as having diabetes, these IDs can provide emergency contact information.

Avoiding Hyperglycemia & Preventing Diabetic Ketoacidosis

The best way to prevent diabetic ketoacidosis is to treat high blood sugar levels appropriately, which means following the diabetes management plan prescribed by the diabetes health care team.

Make sure your child:

  • takes insulin and diabetes medicines as prescribed
  • follows the meal plan and/or makes appropriate adjustments to diabetes medicines when changes to the meal plan are made
  • monitors his or her blood sugar levels regularly and ketone levels when indicated
  • follows the instructions and advice of the diabetes health care team and diabetes management plan, which should include instructions for sick days

By regularly monitoring blood sugar levels, you'll know when your child's blood sugar is high. If that happens, contact the diabetes health care team for more information and to learn how to help bring your child's diabetes back under control.

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